(1) Field of the Invention
The present invention relates to a fixing device which heats and fixes toner onto recording paper as well as relating to an image forming apparatus using the same fixing device.
(2) Description of the Prior Art
Electrophotographic image forming apparatus for forming images based on electrophotography (which will be simply called “image forming apparatus” hereinbelow) can easily produce images of high quality. The image forming apparatus has been widely used for copiers, printers, facsimile machines, multi-functional machines and others. The image forming apparatus includes, for example a photoreceptor, a charging unit, a light exposure unit, a developing unit, a transfer unit and a fixing unit. The image forming apparatus performs the steps of charging, light exposure, developing, transfer and fixing, by means of these components. The image forming apparatus is an apparatus that forms images on recording paper.
As the fixing unit for performing the step of fixing, a fixing device using a belt fixing mechanism has been used for example. The fixing device of a belt fixing mechanism includes a heat roller, a fixing belt, a fixing roller and a pressing roller. The fixing roller and pressing roller are a pair of rollers that press each other with a fixing belt in-between. The heat roller includes a heat source such as a halogen heater or the like as heating equipment therein.
For prevention against meandering of the fixing belt (moving in the longitudinal direction of the heating roller and fixing roller), generally, rotatable move-off stoppers are provided for the heat roller so as to abut the side edges of the fixing belt, to restrain the meandering of the belt. Further, as shown in patent document 1, there is an invention of a method for actively controlling a meandering belt by changing the position of a roller based on a belt meander sensor so as to cancel belt meandering.    Patent Document 1:    Japanese Patent Application Laid-open 2011-123382
However, in the above active control, a sensor for detecting belt meandering, a control circuit and a device for controlling the position of the roller that suspends the belt are needed, thus posing a problem of making the fixing device more complicated and increased in cost.